Bone Mineral Density (BMD) Test
Bone mineral density (BMD) testing can be used to diagnose osteoporosis, detect low bone mass before osteoporosis develops, and help predict your risk of future fractures.
In general, the lower your bone density, the higher your risk for fracture. The results of a bone density test will help guide decisions about starting therapy to prevent or treat osteoporosis. BMD testing may also be used to monitor the effectiveness of ongoing therapy for osteoporosis.
The most widely recognized test for measuring bone mineral density is a quick, painless, noninvasive technology known as dual-energy x-ray absorptiometry (DXA). This technique, which uses low levels of x rays, involves passing a scanner over your body while you are lying on a cushioned table.
DXA can be used to determine BMD of the entire skeleton and at various sites that are prone to fracture, such as the hip, spine, or wrist. Bone density measurement by DXA at the hip and spine is generally considered the most reliable way to diagnose osteoporosis and predict fracture risk.
The doctor will compare your BMD test results to the average bone density of young, healthy people and to the average bone density of other people of your age, sex, and race.
For both women and men, the diagnosis of osteoporosis using DXA measurements of BMD is currently based on a number called a T-score.
Your T-score represents the extent to which your bone density differs from the average bone density of young, healthy people.
- T-score of 1.0 or greater is normal
- T-score between -1.0 and -2.5 represent "low bone mass"
- T-score of -2.5 or below is diagnostic of osteoporosis If you are diagnosed with osteoporosis or very low bone density, or if your bone density is below a certain level and you have other risk factors for fractures, the doctor will talk with you about options for treatment or prevention of osteoporosis.
Reference: The National Institute of Arthritis and Musculoskeletal and Skin Diseases